Potions classes are held in a dungeon classroom, large enough to hold at last twenty students, their cauldrons, and their work tables. The classroom is quite cold, especially in the winter, when students can see their breath. There are pickled animals in glass jars along the walls. There is a basin in the corner of the classroom into which icy cold water pours from a gargoyle's mouth. A student supply cupboard is in the room, along with a blackboard on which the instructor can write directions for student work.

The dungeon passages and rooms under the castle have stone walls and are lit by torches. Nearly Headless Nick held his Deathday Party in one of the "roomier" dungeons. It's dark and dank and many don't venture down here, that is, if they aren't up to no good they won't be found down here.

The Slytherin common room is a long, low-ceilinged, dungeon-like room filled with skulls and the like. There are high-backed chairs and a carved mantlepiece on the fireplace. The walls are rough stone. The light is green from the green hanging lamps and because it's located under the lake.

The Hogwarts kitchens are located directly below the Great Hall and are just the same size. They have high ceilings and a great brick fireplace at one end. Mounds of brass pots and pans are heaped around the walls. There are preparation tables directly below the four house tables in the Hall above, and when the time comes for the food to be served, it is magically transported through the ceiling of the kitchen onto the plates. The kitchens are staffed by over a hundred house-elves. To get to the kitchens, take the door to the right of the main staircase in the entrance hall. Follow the corridor until you come to a painting of a bowl of fruit. Tickle the pear and it giggles and becomes a door handle.